KR20170003236U - Circuit for acoustic distance time of flight compensation - Google Patents

Abstract

In one aspect, the acoustic distance measurement circuit includes a transmitter amplifier for generating an acoustic signal for the acoustic transducer at a first time, a receiver amplifier for detecting a pulse in the acoustic transducer in response to the acoustic signal impinging on the obstacle, Detecting a first time and a first magnitude in response to the edge intersecting the determined threshold, detecting a second magnitude in response to detecting a first peak of the pulse, and responsive to detection of the first magnitude and the second magnitude Determining a flight time of the sound signal within a predetermined distance when the compensation time is extracted from the correction lookup calculation table and providing a compensation time to be subtracted from the first time; And a sensing circuit for sensing the input signal.

Description

[0001] CIRCUIT FOR ACOUSTIC DISTANCE TIME OF FLIGHT COMPENSATION [0002]

BACKGROUND I. Field [0002] The present disclosure relates generally to electrical and electronic circuits, and more particularly to acoustic distance measurement systems.

Acoustic measurement systems and distance measurement systems are used in a variety of applications. For example, acoustic measurement systems are used to measure obstacle distances in applications ranging from automotive systems to fossil discovery. Acoustic measurement systems generally operate by first transmitting a pulse of acoustic energy and generating a sound wave. A measurement of the time of flight of the sound wave is then recorded. The flight time, which is the time from the transmission of the sound wave until the reflection of the sound wave is received, determines the distance of the obstacle. Automotive applications using acoustic measurement systems require reliable detection of the presence of obstacles. At present, reliable detection of obstacles can be hampered by the complex shapes of obstacles as well as by environmental and electrical noise which can lead to false obstacle detection.

Acoustic measurement systems often use acoustic transducers to receive reflected signals or echo signals, as well as to transmit generated acoustic waves. A standard approach to measuring the distance of an obstacle is to report the flight time of the object when the echo signal intersects the threshold. However, the dependence on the time when the echo signal crosses the threshold is not reliable. The reliability of this method may vary depending on the variation of the envelope shape of the echo signal. Also, as the thresholds change, the reported flight times for the same obstacles at the same distance will vary. The accuracy of the sound measurement system is important. Detecting erroneous objects can be detrimental to automotive and other acoustic measurement applications.

Therefore, it is important to avoid distorted object detection associated with the shape of the object, the error in the height of the object, or the error due to the threshold configuration of the detection system. Accuracy in flight time calculation ensures proper acoustic measurement system functions and associated reliability.

BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure may be better understood by reference to the accompanying drawings, and many of its features and advantages may become apparent to those skilled in the art,
1 illustrates, in block diagram form, an acoustic distance measurement system in accordance with one embodiment.
Figure 2 illustrates in block diagram form the acoustic distance measurement circuit for use in the acoustic distance measurement system of Figure 1;
Figure 3 illustrates the sense circuit of Figure 2 in block diagram form.
4 illustrates a timing diagram illustrating acoustic signals received by an acoustic distance measurement system according to an embodiment.
5 illustrates a timing diagram for reporting flight time with a fixed delay over a real time communication bus according to an embodiment.
6 illustrates graphs illustrating the effect of distance variable thresholds when objects are detected at first and second distances for the acoustic sensor of FIG.
7 illustrates a flow chart of a method for reporting compensated flight times for detected obstacles according to an embodiment.
Use of the same drawing protection in different drawings indicates similar or identical items. Unless otherwise stated, the words " coupled "and their associated verb forms include both direct and indirect electrical connections by means known in the art and include, without limitation, The description also suggests alternative embodiments using a suitable type of indirect electrical connection.

For simplicity and clarity of illustration, the elements in the figures are not necessarily drawn to scale, but are schematic and are non-limiting. In addition, the description and details of well-known steps and elements are omitted for the sake of brevity. The terms "during," "during, " and" when "as used herein with respect to circuit operation are not exact terms signifying immediate operation in the start operation, It will be appreciated by those skilled in the art that there may be some small but reasonable delays, such as propagation delays. In addition, the term "during" means that a given operation occurs at least in part of the duration of the initiation operation. The use of the word " approximately "or" substantially "means that the value of an element has a parameter that is expected to approximate the value or position mentioned. However, as is well known in the art, there may be slight variations that can prevent the value or position from being exactly as mentioned.

1 illustrates, in block diagram form, an acoustic distance measurement system 100 in accordance with one embodiment. The acoustic distance measurement system 100 of Figure 1 includes an automotive device 102, a body controller module (BCM) 104, a loudspeaker 164, a set of transmission lines 112, a set of sensors 110, And an obstacle 120. A system controller, such as the BCM 104, is located on or within the automotive device 102 and provides an electrical signal to the loudspeaker 164 corresponding to the audible output.

The automotive device 102 is communicatively coupled to the BCM 104. The BCM 104 has an output for coupling to one or more acoustic transducers, such as sensors 110. The BCM 104 has inputs also coupled to each of the sensors 110. The BCM 104 also has an output for providing an output signal to the loudspeaker 164. In one embodiment, the sensors 110 are ultrasonic sensors that emit ultrasonic pulses that are reflected from the obstacle 120 or acoustic signals as described herein when the obstacle 120 is in the wave field of the acoustic signal. Acoustic signals are generally emitted above the frequencies of the audible sound. The reflected pulse signal or echo is received by the sensor 110. The detection of echoes produces an output signal for use by the BCM 104. Each of the sensors 110 may generate an acoustic signal and sense a reflected pulse signal or echo when hitting the obstacle 120. [

In the illustrated embodiment, the BCM 104 operates as a controller for the acoustic distance measurement system 100 to generate acoustic signals for the sensors 110 at a first time. The sensors 110 are susceptible to receiving echo signals when the transmitted acoustic signal hits an obstacle. The received echo signals are used to define a detectable distance 132. The BCM 104 sends signals to the sensors 110 via the transmission lines 112, and in response, the sensors 110 output acoustic signals. The acoustic signals generated by each sensor 110 travel away from the sensor 110 and propagate through the air. When the BCM 104 stops transmitting acoustic signals, the BCM 104 monitors the sensors 110 for echo signals that may be caused by interception of the propagating acoustic signal. When an obstacle 120 is detected, an echo is received at one of the sensors 110. The received echo signal is processed by the sensor 110 to determine the corrected flight time when the acoustic signal hits the obstacle 120. [ The corrected flight time is transmitted to the BCM 104 via the transmission lines 112. The BCM 104 reports the detection of the object 120 to the surface of the object 120 closest to the sensor 110. Reliable detection of obstacles in various shapes, heights, and unclear dimensions is needed. It is also a desirable feature to avoid false obstacle detection due to varying thresholds during severe noise conditions. The acoustic distance measurement system 100 compensates for these problems as further described.

FIG. 2 illustrates, in block diagram form, an acoustic distance measurement circuit 200 for use in the acoustic distance measurement system of FIG. The acoustic distance measuring circuit 200 includes a controller 204, a frequency generator 208, a transmitter amplifier 212, an acoustic transducer 214, a receiver amplifier 216 and a sensing circuit 220.

Controller 204 is coupled to frequency generator 208. A control signal is output from the controller 204 to the frequency generator 208. In addition, the controller 204 has at least one output terminal for outputting the determined threshold value. The controller 204 has an input terminal for receiving a signal for the corrected flight time. The controller 204 may be, for example, a BCM, an electronic control unit, or a control system operating the acoustic distance measurement system of FIG. The controller 204 is configured to receive the processed corrected time-of-flight signal when the sensing circuit 220 receives the echo signals from the acoustic transducer 214, as well as by outputting the control signal to the frequency generator 208 Thereby operating the acoustic distance measurement system of FIG.

The frequency generator 208 has an input terminal for receiving the control signal, and an output terminal connected to the transmitter amplifier 212. The frequency generator 208 generates an electrical signal that is transmitted to the transducer 214 via the transmitter amplifier 212.

The transmitter amplifier 212 has an input for receiving an electrical signal from the frequency generator 208. The output of the transmitter amplifier 212 coupled to the acoustic transducer 214 is to provide an amplified electrical signal to the acoustic transducer 214.

The sound transducer 214 has an input terminal for receiving the amplified electric signal. Further, the acoustic transducer 214 has an output terminal configured to transmit the generated pulse signal or acoustic signal. The acoustic transducer 214 may be, for example, a piezoelectric sensor.

The receiver amplifier 216 has an input and an output for connection to the acoustic transducer 214. The output of the receiver amplifier 216 coupled to the sense circuit 220 transmits the received pulse signal.

The sensing circuit 220 has an input connected to the output of the receiver amplifier 216, an input for receiving a threshold, and an output for providing a corrected flight time measurement in response to the detection of the threshold. The threshold value is a time-varying signal constituted by the controller 204. The threshold is configured in response to the measured position of the acoustic transducer 214 and the measured effect of the background noise detected by the acoustic transducer 214 to avoid false detection of the obstacle. The determined threshold is used by the sensing circuitry 220 to define the minimum size for the received pulse to cross over the noise level in order to detect an obstacle in response to transmission of the acoustic signal from the acoustic transducer. The sense circuit 220 reports the beginning of the echo or pulse signal as flight time, where the beginning of the pulse signal represents the nearest obstacle surface to acoustic transducer 214. [

In operation, the controller 204 provides a control signal to the frequency generator 208. At a first time, the frequency generator 208 generates a signal and provides the generated signal to the transmitter amplifier 212 as an electrical signal. The transmitter amplifier 212 amplifies the power of the signal generated by the frequency generator 208 and provides an electrical signal to the acoustic transducer 214. If the transmitter amplifier 212 is not implemented, the frequency generator 208 provides the un-amplified signal to the sound transducer 214. The sound transducer 214 vibrates and generates a signal corresponding to the provided input signal. The acoustic signal generated by the acoustic transducer 214 vibrates and travels away from the acoustic transducer 214. [ The receiver amplifier 216 monitors the acoustic transducer 214 for the echo signals, amplifies the received echo signals, and then transmits the pulse signal to the sensing circuit 220. The sensing circuit 220 uses the received pulse signal in addition to the input of the threshold to determine the corrected flight time of the acoustic signal. The calibrated flight time is reported to the controller 204.

3 illustrates in block diagram form a sensing circuit 300 that may be used as the sensing circuit 220 of FIG. The sensing circuit 300 generally includes a controller 204, an analog-to-digital converter 320, a digital filter 322, a rising edge detector 324, a peak detector 326, a correction algorithm module 328, A quality (Q) factor delay value block 322, a flight time algorithm module 334 and a converter quality (Q) factor delay value block 336. The quality factor (Q)

Analog-to-digital converter 320 has an input coupled to an output of a receiver amplifier (e.g., receiver amplifier 216 of FIG. 2) for receiving an input signal, and an output. The digital filter 322 includes an input coupled to the output of the analog-to-digital converter 320, an output for providing a Q factor time delay value in the Q factor delay value block 332, and an output for providing a filtered signal .

The rising edge detector 324 provides an input coupled to the output of the digital filter 322 and a first magnitude and first time when the rising edge of the pulse signal received from the digital filter 322 crosses the threshold Lt; / RTI >

Peak detector 326 has an input coupled to the output of digital filter 322 and an output to provide magnitude of the pulse signal received from digital filter 322 at peak time. The magnitude of the pulse signal is received in response to detecting the obstacle within a predefined distance to the acoustic transducer in accordance with the filtered pulse signal.

Calibration algorithm module 328 has an input coupled to a rising edge detector and a peak detector, and an output to provide a correction ratio. The correction ratio is the ratio of the first magnitude of the rising edge of the magnitude of the pulse received from the receiver amplifier at the first time to the threshold and the magnitude of the pulse received from the acoustical converter at the peak time.

The flight time correction calculation module 330 includes an input coupled to the output of the correction algorithm module 328, an input for receiving the output of the digital filter Q factor time delay value block 332, an acoustic transducer Q factor time delay value block 336, and a compensation time for calculating a corrected flight time of the acoustic signal in response to impinging on the obstacle in a first position within a predefined distance for the acoustic transducer, according to the filtered signal, Lt; / RTI >

The flight time module 334 includes an input coupled to the output of the peak detector 326, an input coupled to the output of the flight time correction calculation module 330, and a corrected flight of the acoustic signal in response to the acoustic signal impinging on the obstacle And has an output to provide time.

In operation, the sensing circuitry 300 receives an input signal, which is generated from reflections from the echo signals provided by the acoustic transducer 214 (of FIG. 2) Lt; / RTI > receiver amplifier 216). The sensing circuit 300 filters the signal received from the acoustic transducer 214 and provides an output corresponding to the corrected flight time of the acoustic signals for the acoustic signal transmitted via the acoustic transducer 214. The controller 204 sends the configured threshold to the sense circuit. The analog-to-digital converter 320 digitizes the received input signal. The digital filter 322 receives the digitized input signal and provides a filtered pulse signal to a rising edge detector 324 and a peak detector 326. The rising edge of the filtered pulse signal is detected by the rising edge detector 324 at the point where the rising edge crosses the threshold. In response to detecting the rising edge of the pulse, the time at which the rising edge intersects the threshold, and the magnitude at which the rising edge meets the threshold, is stored for use in calculating the corrected flight time. The peak detector 326 detects the peak magnitude of the filtered pulse signal. In response to detecting the peak magnitude of the pulse, the peak detector 326 stores the peak magnitude as a second magnitude for use in determining the corrected flight time. Peak detection is performed following a filtered pulse signal passing a threshold at a first time and is valid while the filtered pulse signal is above a threshold.

Further, after detecting the magnitude when the rising edge crosses the threshold (first magnitude) and the peak magnitude (second magnitude) of the filtered signal, the first and second detected magnitudes are used to calculate the corrected flight time . The ratio of the first size to the second size is determined by the correction algorithm module 328. The ratio of the first size to the second size is multiplied by a factor of 100. The value of the determined ratio is used in the flight time correction calculation module 330. In the flight time correction calculation module 330, a compensation time is additionally determined using a correction lookup table or a correction algorithm. The compensation time is the amount of time used to adjust the initially detected flight time. The adjustment using the compensation time determines a corrected start of the pulse in response to the acoustic signal impinging on the obstacle.

Also, at least one of the Q factor delay 332 and the converter Q factor delay 336 may be used to calculate the flight time correction (e. G., ≪ RTI ID = 0.0 & 330). ≪ / RTI > The flight time algorithm module 334 determines whether the compensation time provided by the output of the flight time correction calculation module 330 is such that the rising edge of the magnitude of the pulse received from the receiver amplifier, as determined at the rising edge detector 324, And provides the controller 204 with a corrected flight time when subtracted from the first time when it intersects with the first time.

In one embodiment, the Q factor time delay of the digital filter 322 and the converter 214 determines the maximum time to receive the transmission of the pulse measurements before the flight time measurements are provided to the controller 204. [ The digital filter quality factor time delay 332 determines the time delay required for the sensing circuit 300 to provide the calibrated flight time to the controller 204 at the correct timing. The value of the digital filter Q factor time delay 332 is dynamically selected when the first magnitude of the pulse is detected at the rising edge detector 324. As an increase in digital filter Q factor time delay 332 is detected, the response time of digital filter 322 automatically increases. However, in response to the detection of a value for the digital filter Q factor time delay 332 that is lower than the predetermined Q factor time delay value, the converter Q factor time delay 336 is dynamically entered when the magnitude of the pulse is detected. By incorporating the dynamically determined fixed delay into the flight time correction algorithm, the sensing circuit can appropriately compensate for the time required to transmit the corrected flight time to the controller 204, thereby maintaining accurate real-time reporting of the corrected flight time The accuracy of obstacle detection can be increased.

In another embodiment, the digital filter Q factor is fixed when the transducer 214 receives the echo pulse signal. The digital filter Q factor is selected to improve the performance of the sensing circuit 300. For example, the digital filter Q factor is a predetermined Q factor in the range of Q5 to Q20. A high value for the digital filter 322 enables the digital filter 322 to achieve a high signal-to-noise ratio or increased noise suppression. However, the Doppler performance of the digital filter 322 is less than optimal when a high Q factor value is selected. When a low value for the digital filter Q factor is selected, the Doppler performance of the sensing circuit 200 is better; However, the signal to noise ratio is low, allowing less noise to be suppressed. The pulse rise time depends on the selected Q factor of the digital filter 322; Accordingly, the digital filter Q factor time delay 332 is a factor when reporting the corrected flight time of the acoustic signal to the controller 204. [ For example, for the quality factor value of Q5 for the digital filter 322, the time the pulse signal rises from 50% to 100% is the pulse signal rising from 50% to 100% in the case of the Q10 quality factor value Half of the time it takes. For low Q digital filter settings, the converter Q factor time delay 336 is used to determine the corrected flight time. In one embodiment, the value for the digital filter Q factor is a predetermined Q factor value. The digital filter Q factor is selected before the start of the measurement and maintains the same Q factor for the duration of the measurement. In another embodiment, at least one of the low Q factor and the high Q factor is selected to correspond to a predefined measurement distance. In one example, reflections received from obstacles at close distances (e.g., less than 2.4 meters) benefit from an improved signal-to-noise ratio; Accordingly, a higher (or increased) Q factor is applied.

FIG. 4 illustrates a flight time correction diagram 400 that represents the filtered pulse signal received by the sensing circuit 300 of FIG. 3, and an exemplary calibration lookup table 440. Within flight time correction diagram 400, time is displayed on time axis 412 and the vertical axis represents the size (in volts) of the various signals. The flight time diagram 400 also includes a pulse measurement waveform 406, a threshold size 404, a peak size 402, a waveform 408 showing the echo comparison signal, a waveform 410 showing the corrected echo comparison signal, Compensation time 418, flight time measurement 414, and rising edge time 416. The exemplary calibration look-up table 440 includes a compensation time 418 and a correction ratio 442.

The flight time correction diagram 400 shows the correction applied to the filtered pulse 406. The rising edge detector 324 detects when the pulse measurement 406 crosses the threshold size 404 and the magnitude at the crossing point is recorded as the first magnitude. The second magnitude, peak magnitude 402, detected by the peak detector 326 is recorded as the highest peak of the pulse measurement 406 before the pulse signal crosses the threshold 404 at the second time. After receiving the threshold size 404 and the peak size 402, the correction algorithm 328 determines the value of the correction ratio 442. The correction ratio 442 determines the compensation time 418 by selecting a value of the correction ratio 442 on the graph plot with a finite selection of points and then compensates for the values associated with the exemplary correction lookup table 440 Is used to determine the time 418. The flight time correction calculation 330 determines the compensation time 418. Although an exemplary lookup table is used in this example, an algorithm may be used to determine the compensation time 418 without the use of a lookup table. The flight time measurement 414, which is also the corrected flight time, is calculated by subtracting the compensation time 418 from the rising edge time 416 as provided in the flight time algorithm 334. [ The calibrated flight time is reported to the controller 204. The waveform 408 and waveform 410 in the flight time correction diagram 400 show a tremendous adjustment time associated with calculating the corrected flight time when the pulse measurement 406 is received.

Figure 5 illustrates a timing diagram 500. Timing diagram 500 includes pulse signal 510, input / output (I / O) line communication 520, and I / O line communication 530. The pulse signal 510 located on the y-axis 502 and x-axis 512 includes a peak detection 508, a threshold 504, a flight time 514, a first detection 516, (518). I / O line communication 520 includes y-axis 502, x-axis 512, signal 522, and post-detection fixed delay 524. The I / O line communication 530 includes y-axis 502, x-axis 512, signal 532, and Q-factor time delay 534.

Within the timing diagram 500, a pulse signal 510 is received at the transducer 214 when the transmitted acoustic signal hits an obstacle. The magnitude of the pulse signal 510 is reported on the y-axis 502. The time range of the pulse signal measurement is reported on the y-axis. Threshold 504 represents a magnitude sufficient to detect the presence of an obstacle. At the first detection 516, the magnitude of the received pulse intersects the threshold 504. Peak detection 508 is the maximum detection point of the obstacle above threshold 504. Obstacle detection is active while the pulse signal 510 is above the threshold 504.

The I / O line communication 520 shows how the pulse signal 510 is delivered through the I / O line when a fixed post-measurement delay is applied. For example, when a pulse signal crosses a threshold value 504, the pulse signal 510 crosses the threshold at the first detection 516 and is received as a signal 522 having a falling edge through the I / 204). The low pulse identifies the width of the pulse signal 510 corresponding to the detection time 518. The I / O line rising edge illustrated as the fixed delay 524 indicates that the pulse signal 510 falls below the threshold 504 and thereby corresponds to the delay time for reporting the flight time to the controller 204 Identify when.

As an alternative to this post-measurement fixed delay, the sensing circuit 300 reflects the Q factor fixed delay during the reception of the pulse signal 510 to the algorithm of the corrected flight time. The IO line communication 530 shows how the pulse signal 510 is delivered through the IO line when a Q factor fixed delay is associated with the sensing circuit 300. For example, the pulse signal 510 is indicated by the signal 532 as the falling edge when the pulse signal 510 falls below the threshold 510. The falling edge of signal 532 corresponds to the completion of detection time 518. The Q factor delay 534 is reflected in the detection time 518; Accordingly, additional delay such as fixed delay 524 is avoided.

To further illustrate the reflection of the Q factor time delay to the detection time 518, in one example, the Q factor time delay 534 is determined when the pulse signal 516 crosses the threshold 504. The pulse signal 510 is received at the converter 214. In response to receiving the first detection 516, the duration of the Q factor time delay 534 is determined. The Q factor time delay 534 determines the maximum time to receive the transmission of the pulse signal 510 before the flight time measurement 514 is provided to the controller 205. The sensing circuit 330 determines when the Q factor time delay 534 is greater than the detection time 518. [ In response to the Q factor time delay 534 being less than the detection time 518, the Q factor time delay is increased dynamically to increase the response time of the associated component, such as the digital filter 322 and the converter 214. In response to the Q factor time delay 534 being greater than the detection time 518, a corrected Q factor time delay is provided. In one embodiment, a predetermined fixed time delay is used corresponding to the maximum Q factor of at least one of the digital filter 322 and the converter 214.

Figure 6 shows a chart showing the effect of a distance variable threshold when an object is detected at first and second distances for an acoustic sensor. The flight time compensation chart 600 includes distance 610, threshold 612, piezo A deactivation 602, piezo B deactivation 604, piezo A activation 606 and piezo B activation 608. The flight time compensation chart 630 includes distance 610, threshold 612, piezo A deactivation 632, piezo B deactivation 634, piezo A activation 636, and piezo B activation 638.

The flight time compensation chart 600 shows sensors, e. G., Amplitude modulation sensors and frequency chirp sensors, that receive an echo signal when hitting an obstacle at a distance of 2 meters during flight time measurement. In the flight time compensation chart 600, the distance 610 is the measured distance of the obstacle in centimeters, the threshold 612 corresponds to the change in the magnitude of the reported threshold, and the piezo A deactivation 602 Corresponds to a piezoelectronic device, for example a frequency chirp sensor, in which the flight time compensation is deactivated. Likewise, piezo B inactivity 604 corresponds to a piezoelectronic device, e.g., an amplitude modulation sensor, in which flight time compensation is also deactivated. Similarly, the piezo A activation 606 and the piezo B activation 608 correspond to the frequency chirp sensor and the amplitude modulation sensor, respectively, in which flight time compensation is activated.

In the example of the flight time compensation chart 600, the piezo A inactivity 602 and the piezo B inactivity 604 simulate a change of nearly 3 cm when the predetermined threshold varies from 10 to 60 for the size of the threshold 612 do. In contrast, in the case of the piezo A activation 606 and the piezo B activation 608, a negligible change of 1 cm is identified when the predetermined threshold varies from 10 to 60 for the size of the threshold 612. Activation of flight time compensation increases the accuracy of the measurement by at least 2 cm. Also, the activation of the flight time compensation shows that the flight time is not significantly affected by the predetermined threshold when the flight time compensation is activated.

The flight time compensation chart 630 shows sensors, e. G., Amplitude modulation sensors and frequency chirp sensors, that receive an echo signal when hitting an obstacle at a distance of 3 meters during flight time measurement. Within the flight time compensation chart 630, the distance 610 corresponds to the measured distance of the obstacle in centimeters, the threshold 612 corresponds to the change in the magnitude of the reported threshold, and the piezo A deactivation 632 Corresponds to a piezoelectronic device, for example a frequency chirp sensor, in which the flight time compensation is deactivated. Similarly, piezo B inactivation 634 corresponds to a piezoelectronic device, e.g., an amplitude modulation sensor, in which the flight time compensation is also deactivated. Similarly, piezo A activation 636 and piezo B activation 638 correspond to frequency chirp sensors and amplitude modulation sensors, respectively, in which flight time compensation is activated.

In the example of the flight time compensation chart 630, the piezo A inactivation 632 and the piezo B inactivation 634 are characterized by a change of approximately 2 to 3 cm when the predetermined threshold varies from 10 to 60 for the size of the threshold 612 Lt; / RTI > In contrast, in the case of the piezo A activation 636 and the piezo B activation 638, a negligible change of less than 1 cm is identified when the predetermined threshold varies from 10 to 60 for the size of the threshold 612. As the distance between the sensor and the detectable object increases, the activation of flight time compensation increases the accuracy of the measurement by at least 2 cm. Also, once again, activation of flight time compensation indicates that flight time is not affected by a predetermined threshold when flight time compensation is activated.

FIG. 7 shows a flow diagram of a method 700 for detecting an obstacle with flight time compensation activated. At block 702, a sound signal for the sound transducer is generated at a first time. In block 704, in response to the acoustic signal impinging on the obstacle, a pulse is detected in the acoustic transducer. At block 706, a time when the rising edge of the pulse intersects the threshold is detected. At block 908, the first magnitude and first time of the pulse at the intersection point are stored. At block 710, the peak magnitude of the received pulse is detected. At block 712, the peak magnitude is stored as the second magnitude of the received pulse. At block 714, a ratio of the first size to the second size, multiplied by 100, is provided in the correction look-up table. At block 716, the compensation time is extracted from the correction lookup table. At block 718, this compensation time is subtracted from the first time to determine the compensated flight time. At block 720, the first position of the obstacle is determined because the compensated flight time corresponds to the first position of the obstacle. At block 722, the compensated flight time is reported to the controller at a time equal to or less than the Q factor time delay. The process ends at the end block.

While the subject matter has been described in conjunction with specific preferred embodiments and illustrative embodiments, it is to be understood that the drawings and description thereof are not to be taken as illustrative only of typical embodiments of the subject matter and are therefore not to be considered limiting of its scope, And variations will be apparent to those skilled in the art. The inventive aspects of the present disclosure may lie in less than all features of a single single disclosed embodiment.

According to one embodiment, the acoustic distance measurement circuit includes a transmitter amplifier, a receive amplifier, a controller, and a sense circuit. The transmitter amplifier has an output coupled to and configured to provide an acoustic signal to the acoustic transducer and provide acoustic transducer quality factor time delay. The receiver amplifier has an input coupled to the acoustic transducer and configured to receive a pulse, and an output. The controller provides a threshold for defining a time-varying magnitude signal in response to the dimensional position of the acoustical transducer and in response to the measured effect of the background noise detected by the acoustic transducer. The sensing circuit has an input coupled to the output of the receiver amplifier and an output for providing a corrected flight time measurement in response to the detection of the threshold. The sensing circuitry defines the time at which the acoustic signal travels to the first location of the obstacle in response to transmission of the acoustic signal from the acoustic transducer and detects an obstacle within a predefined distance to the acoustic transducer.

According to one aspect of this embodiment, the sensing circuit comprises a digital filter having an input coupled to an output of the receiver amplifier, an output for providing a filtered signal, and an output for providing a digital filter quality factor time delay, And a rising edge detector having an input coupled to the output of the digital filter and having an output to provide a first time and a first magnitude when the rising edge of the pulse received from the receiver amplifier crosses the threshold, And a peak detector having an output for providing a magnitude of a pulse received from the receiver amplifier at peak time in response to detecting an obstacle within a predefined distance for the acoustic transducer in accordance with the filtered signal. According to this aspect, the sensing module may include a first correction module and a flight time correction module, wherein the first correction module has an input coupled to the rising edge detector and the peak detector, and an output for providing a correction ratio , The correction ratio is the ratio of the first magnitude of the rising edge of the magnitude of the pulse received from the receiver amplifier to the threshold and the magnitude of the pulse received from the acoustical converter at the peak time, An input coupled to the output of the correction module, an input for receiving a digital filter quality factor time delay, an input for receiving an acoustic transducer quality factor time delay, In order to provide a compensation time for calculating the corrected flight time of the acoustic signal in response to hitting the obstacle at position 1 And has one output.

According to another aspect, the sensing circuit includes an input coupled to the output of the peak detector, an input coupled to the output of the flight time correction calculation module, and an input coupled to the output of the flight time correction calculation module to provide a corrected flight time of the acoustic signal in response to the acoustic signal impinging on the obstacle And a flight time module having an output. In this case, the first correction module may also multiply the ratio by a factor of 100. The flight time module also provides a compensated flight time when the compensation time provided by the output of the flight time correction calculation module is subtracted from the first time when the rising edge of the magnitude of the pulse received from the receiver amplifier crosses the threshold can do. The digital filter quality factor time delay can be dynamically selected when the magnitude of the pulse is detected.

According to another aspect, the digital filter quality factor time delay can dynamically determine the delay time of the sensing circuit. If so, in response to the detection of a digital filter quality factor time delay less than a predetermined quality factor time delay, the converter quality factor time delay can be dynamically entered when the magnitude of the pulse is detected. In addition, as an increase in the digital filter quality factor time delay is detected, the response time of the digital filter can be automatically increased.

In another embodiment, the acoustic distance comprises a transmitter amplifier, a receiver amplifier and a sensing circuit. The transmitter amplifier is for generating an acoustic signal for the acoustic transducer at a first time, wherein the acoustic transducer transmits an acoustic signal to determine a first position of the obstacle. The receiver amplifier is for detecting a pulse in the acoustic transducer in response to the acoustic signal impinging on the obstacle within a predetermined distance. The sensing circuit detects a first time and a first magnitude in response to the rising edge of the pulse intersecting the determined threshold and detects a second magnitude in response to detecting a first peak of the pulse, To determine a flight time of the acoustic signal within a predetermined distance when the compensation time is extracted from the correction lookup calculation table in response to the detection of the two sizes and to provide a compensation time to be subtracted from the first time, The difference in the first time is the flight time.

According to one aspect of this embodiment, a first position of an obstacle within a predetermined distance is estimated, wherein the flight time corresponds to the detection of the first position of the obstacle.

According to another aspect, the rising edge of the pulse is detected, and in response to detecting the rising edge of the pulse at the determined threshold, the first time and the first magnitude are stored. According to this aspect, a first peak of the pulse can be detected, wherein the first peak of the pulse is of a second magnitude, and in response to detecting the first peak of the pulse, the second magnitude is stored. In this case, a ratio of the first magnitude to the second magnitude may be detected, and determining the ratio further comprises providing a ratio of the first magnitude to the second magnitude, multiplied by a factor of 100, to the correction lookup calculation table can do. In this case, the compensation time may be extracted from the correction lookup calculation table, where the compensation time corresponds to a ratio of the first size to the second size in the correction lookup calculation table.

In accordance with another aspect, in response to receiving a first magnitude when a pulse crosses a determined threshold, a quality factor time delay may be determined in response to an acoustic signal crossing an obstacle, Wherein the quality factor time delay determines the maximum time to receive the transmission of the pulse measurements before the flight time measurements are provided to the controller. According to this aspect, the time when the quality factor time delay is greater than the peak detection time can be determined, and in response to the quality factor time delay being less than the peak detection time, the quality factor time delay is dynamically increased, The response time of the filter can be increased and the corrected quality factor time delay can be provided as the maximum flight time reporting time adjusted to the controller.

According to another aspect, programmable values corresponding to the determined threshold may be received, wherein the determined threshold is a time-varying threshold.

According to a further aspect, the acoustic signal from the acoustic transducer may be filtered to provide a filtered signal, and the obstacle may be detected in response to receipt of the filtered signal.

Moreover, some embodiments described herein include some features, but not other features, included in other embodiments, and thus, as will be appreciated by those skilled in the art, combinations of features of different embodiments Are intended to be within the scope of this disclosure and constitute a different embodiment.

Claims (5)

An acoustic distance measuring circuit comprising:
A transmitter amplifier coupled to the acoustic transducer and having an output configured to provide an acoustic signal to the acoustic transducer and provide an acoustic transducer quality factor time delay;
A receiver amplifier coupled to the acoustic transducer and having an input configured to receive a pulse and an output;
A controller for providing a threshold for defining a time-varying magnitude signal in response to a dimensional position of the acoustic transducer and in response to a measured effect of the background noise detected by the acoustic transducer; And
Wherein the acoustic signal has an input coupled to the output of the receiver amplifier and an output for providing a corrected flight time measurement responsive to the detection of the threshold, wherein in response to the transmission of the acoustic signal from the acoustic transducer, And a sensing circuit for detecting an obstacle within a predefined distance to the acoustic transducer,
And an acoustic distance measuring circuit. 2. The semiconductor memory device according to claim 1,
A digital filter having an input coupled to the output of the receiver amplifier, an output for providing a filtered signal, and an output for providing a digital filter quality factor time delay;
A rising edge detector having an input coupled to the output of the digital filter and an output to provide a first time and a first magnitude when the rising edge of the pulse received from the receiver amplifier crosses the threshold; And
In response to detecting an obstacle within the predefined distance to the acoustic transducer in response to the filtered signal, an input coupled to the output of the digital filter, A peak detector having an output for providing a magnitude
And an acoustic distance measuring circuit. 3. The semiconductor memory device according to claim 2,
A first correction module having an input coupled to the rising edge detector and an input coupled to the peak detector and an output for providing a correction ratio, the correction ratio comprising a rising edge of the magnitude of the pulse received from the receiver amplifier, Said first magnitude when crossing and the ratio of said magnitude of said pulse received from said acoustical converter at said peak time; And
An input coupled to the output of the first correction module, an input for receiving the digital filter quality factor time delay, an input for receiving the acoustic transducer quality factor time delay, A flight time correction calculation module having an output for providing a compensation time for calculating a corrected flight time of an acoustic signal in response to impinging on the obstacle in a first position within the predefined distance,
And an acoustic distance measuring circuit. An acoustic distance measuring circuit comprising:
A transmitter amplifier for generating an acoustic signal for the acoustic transducer at a first time, the acoustic transducer transmitting the acoustic signal to determine a first position of the obstacle;
A receiver amplifier for detecting a pulse in the acoustic transducer in response to the acoustic signal impinging on the obstacle within a predetermined distance; And
Detecting a first time and a first magnitude in response to the rising edge of the pulse intersecting the determined threshold,
Detecting a second magnitude in response to detecting a first peak of the pulse,
Determine a flight time of the acoustic signal within the predetermined distance when a compensation time is extracted from the correction lookup calculation table in response to the detection of the first magnitude and the second magnitude,
Providing the compensation time to be subtracted from the first time, wherein the difference between the compensation time and the first time is the flight time
Sensing circuit
And an acoustic distance measuring circuit. An acoustic distance measurement system,
A transmitter amplifier for providing an acoustic signal thereto and providing an acoustic transducer quality factor time delay;
A receiver amplifier for receiving a pulse;
A controller for providing a threshold for defining a time-varying magnitude signal in response to a dimensional position of the acoustic transducer and in response to a measured effect of the background noise detected by the acoustic transducer;
Providing a corrected flight time measurement in response to detecting the threshold and defining a time at which the acoustic signal travels to a first position of the obstacle in response to transmission of the acoustic signal from the acoustic transducer, A sensing circuit for sensing an obstacle within a predefined distance;
A digital filter for providing a filtered signal and a digital filter quality factor time delay;
A rising edge detector for providing a first time and a first magnitude when the rising edge of the pulse received from the receiver amplifier crosses the threshold;
A peak detector for providing a magnitude of the pulse received from the receiver amplifier at a peak time in response to detecting an obstacle within the predefined distance for the acoustic transducer in accordance with the filtered signal;
A first correction module for providing a correction ratio;
A flight time correction calculation for providing a compensation time for calculating a corrected flight time of the acoustic signal in response to impinging on the obstacle in a first position within the predefined distance for the acoustic transducer in response to the filtered signal; module; And
A flight time module for providing the corrected flight time of the acoustic signal in response to the acoustic signal impinging on the obstacle;
And an acoustic distance measurement system.

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